/*!
 * Lazy Load - jQuery plugin for lazy loading images
 *
 * Copyright (c) 2007-2015 Mika Tuupola
 *
 * Licensed under the MIT license:
 *   http://www.opensource.org/licenses/mit-license.php
 *
 * Project home:
 *   http://www.appelsiini.net/projects/lazyload
 *
 * Version:  1.9.7
 *
 */

(function ($, window, document, undefined) {
  var $window = $(window)

  $.fn.lazyload = function (options) {
    var elements = this
    var $container
    var settings = {
      threshold: 0,
      failure_limit: 0,
      event: 'scroll',
      effect: 'show',
      container: window,
      data_attribute: 'original',
      skip_invisible: false,
      appear: null,
      load: null,
      placeholder: ''
    }

    function update () {
      var counter = 0

      elements.each(function () {
        var $this = $(this)
        if (settings.skip_invisible && !$this.is(':visible')) {
          return
        }
        if ($.abovethetop(this, settings) ||
                    $.leftofbegin(this, settings)) {
          /* Nothing. */
        } else if (!$.belowthefold(this, settings) &&
                    !$.rightoffold(this, settings)) {
          $this.trigger('appear')
          /* if we found an image we'll load, reset the counter */
          counter = 0
        } else {
          if (++counter > settings.failure_limit) {
            return false
          }
        }
      })
    }

    if (options) {
      /* Maintain BC for a couple of versions. */
      if (undefined !== options.failurelimit) {
        options.failure_limit = options.failurelimit
        delete options.failurelimit
      }
      if (undefined !== options.effectspeed) {
        options.effect_speed = options.effectspeed
        delete options.effectspeed
      }

      $.extend(settings, options)
    }

    /* Cache container as jQuery as object. */
    $container = (settings.container === undefined ||
                      settings.container === window) ? $window : $(settings.container)

    /* Fire one scroll event per scroll. Not one scroll event per image. */
    if (settings.event.indexOf('scroll') === 0) {
      $container.bind(settings.event, function () {
        return update()
      })
    }

    this.each(function () {
      var self = this
      var $self = $(self)

      self.loaded = false

      /* If no src attribute given use data:uri. */
      if ($self.attr('src') === undefined || $self.attr('src') === false) {
        if ($self.is('img')) {
          $self.attr('src', settings.placeholder)
        }
      }

      /* When appear is triggered load original image. */
      $self.one('appear', function () {
        if (!this.loaded) {
          if (settings.appear) {
            var elements_left = elements.length
            settings.appear.call(self, elements_left, settings)
          }
          $('<img />')
            .bind('load', function () {
              var original = $self.attr('data-' + settings.data_attribute)
              $self.hide()
              if ($self.is('img')) {
                $self.attr('src', original)
              } else {
                $self.css('background-image', "url('" + original + "')")
              }
              $self[settings.effect](settings.effect_speed)

              self.loaded = true

              /* Remove image from array so it is not looped next time. */
              var temp = $.grep(elements, function (element) {
                return !element.loaded
              })
              elements = $(temp)

              if (settings.load) {
                var elements_left = elements.length
                settings.load.call(self, elements_left, settings)
              }
            })
            .attr('src', $self.attr('data-' + settings.data_attribute))
        }
      })

      /* When wanted event is triggered load original image */
      /* by triggering appear.                              */
      if (settings.event.indexOf('scroll') !== 0) {
        $self.bind(settings.event, function () {
          if (!self.loaded) {
            $self.trigger('appear')
          }
        })
      }
    })

    /* Check if something appears when window is resized. */
    $window.bind('resize', function () {
      update()
    })

    /* With IOS5 force loading images when navigating with back button. */
    /* Non optimal workaround. */
    if ((/(?:iphone|ipod|ipad).*os 5/gi).test(navigator.appVersion)) {
      $window.bind('pageshow', function (event) {
        if (event.originalEvent && event.originalEvent.persisted) {
          elements.each(function () {
            $(this).trigger('appear')
          })
        }
      })
    }

    /* Force initial check if images should appear. */
    $(document).ready(function () {
      update()
    })

    return this
  }

  /* Convenience methods in jQuery namespace.           */
  /* Use as  $.belowthefold(element, {threshold : 100, container : window}) */

  $.belowthefold = function (element, settings) {
    var fold

    if (settings.container === undefined || settings.container === window) {
      fold = (window.innerHeight ? window.innerHeight : $window.height()) + $window.scrollTop()
    } else {
      fold = $(settings.container).offset().top + $(settings.container).height()
    }

    return fold <= $(element).offset().top - settings.threshold
  }

  $.rightoffold = function (element, settings) {
    var fold

    if (settings.container === undefined || settings.container === window) {
      fold = $window.width() + $window.scrollLeft()
    } else {
      fold = $(settings.container).offset().left + $(settings.container).width()
    }

    return fold <= $(element).offset().left - settings.threshold
  }

  $.abovethetop = function (element, settings) {
    var fold

    if (settings.container === undefined || settings.container === window) {
      fold = $window.scrollTop()
    } else {
      fold = $(settings.container).offset().top
    }

    return fold >= $(element).offset().top + settings.threshold + $(element).height()
  }

  $.leftofbegin = function (element, settings) {
    var fold

    if (settings.container === undefined || settings.container === window) {
      fold = $window.scrollLeft()
    } else {
      fold = $(settings.container).offset().left
    }

    return fold >= $(element).offset().left + settings.threshold + $(element).width()
  }

  $.inviewport = function (element, settings) {
    return !$.rightoffold(element, settings) && !$.leftofbegin(element, settings) &&
                !$.belowthefold(element, settings) && !$.abovethetop(element, settings)
  }

  /* Custom selectors for your convenience.   */
  /* Use as $("img:below-the-fold").something() or */
  /* $("img").filter(":below-the-fold").something() which is faster */

  $.extend($.expr[':'], {
    'below-the-fold': function (a) { return $.belowthefold(a, { threshold: 0 }) },
    'above-the-top': function (a) { return !$.belowthefold(a, { threshold: 0 }) },
    'right-of-screen': function (a) { return $.rightoffold(a, { threshold: 0 }) },
    'left-of-screen': function (a) { return !$.rightoffold(a, { threshold: 0 }) },
    'in-viewport': function (a) { return $.inviewport(a, { threshold: 0 }) },
    /* Maintain BC for couple of versions. */
    'above-the-fold': function (a) { return !$.belowthefold(a, { threshold: 0 }) },
    'right-of-fold': function (a) { return $.rightoffold(a, { threshold: 0 }) },
    'left-of-fold': function (a) { return !$.rightoffold(a, { threshold: 0 }) }
  })
})(jQuery, window, document)
